A fixed supply radio frequency (RF) power amplifier (PA) operates with a fixed supply voltage and amplifies an input or transmit signal for RF transmission. The fixed supply PA may operate efficiently for higher valued signals. However, the fixed supply PA typically operates inefficiently at lower values.
Furthermore, the fixed supply PA may be efficient for higher input values or ranges, but these high values can lead to compression and introduce nonlinearities into an amplified output signal. Thus, when the fixed supply PA can operate more efficiently, nonlinearities are introduced into its output.
Envelope tracking is an alternative approach that utilizes a non-fixed supply PA. Envelope tracking may provide more power efficiency at lower signal levels as compared with fixed supply PAs. However, envelope tracking across large channel widths and/or certain frequencies can be problematic.